By: Bonnie L. Grant, Certified Urban Agriculturist
Compost is an inexpensive and renewable soil amendment. It is easy to make in the home landscape from leftover kitchen scraps and plant material. However, keeping an odorless compost bin takes a little effort. Managing compost odors means balancing the nitrogen and carbon in the material and keeping the pile moderately moist and aerated.
What causes stinky compost piles? Organic waste breaks down with the help of bacteria, microbes and small animals, such as snails and worms. All of this life needs oxygen to survive and decompose the material. Additionally, a careful balance of nitrogen and carbon is necessary for an odorless compost bin. Moisture is another factor and certain food items, such as meat, should be avoided, as they take longer to compost and can leave bad bacteria in the resulting material.
Anything that was once alive is compostable. Meat and bones take longer and shouldn’t go in unless you really know what you are doing. The four important factors in composting are the material, water, oxygen and heat. Without a careful balance of these four parts, the result may be stinky compost piles.
The material in the pile should be about one-quarter nitrogen-rich items and three-quarters carbon-rich items. Nitrogen-rich items are usually green and carbon materials are generally brown, so make sure your compost heap is evenly balanced with greens and browns. Nitrogen sources are:
Carbon sources would be:
The pile should be kept moderately moist but never soggy. Turning the pile frequently exposes it to oxygen for the bacteria and animals that are doing all the work. Compost needs to get up to 100 to 140 degrees Fahrenheit (37-60 C.) for best decomposition. You can enhance the temperature by using a black bin or covering a pile with dark plastic.
Odor management in compost is the result of this careful balance of organic material and conditions. If one aspect is not stable, the whole cycle is thrown off and odors may result. For instance, if the compost is not warm enough, the heat loving microbes (which are responsible for the initial break down of the material) will not be present. That means the materials will simply sit there and rot, which brings about odors.
The microbes and other organisms that break down the material give off carbon dioxide and heat during the aerobic respiration process. This enhances solar heat and encourages more bacteria and microbes for quicker composting. Smaller pieces compost more quickly, reducing any odors. Woody material should only be ¼-inch (.6 cm.) in diameter and food scraps should be cut into small pieces.
Odors such as ammonia or sulfur are indicative of an unbalanced pile or incorrect conditions. Check to see if the pile is too soggy and add dry soil to correct this.
Odor management in compost is easy with a carefully maintained equilibrium of the four composting factors.
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Read more about Composting Basics
The decomposing material in a compost pile emits a natural, earthy scent, but strong or offensive odors often signal a problem. The contents of the compost pile are usually to blame for the strong smell. An ammonia odor wafts from a pile with nitrogen levels that are too high, while a rotten odor often comes with excessive amounts of kitchen scraps. A properly maintained compost pile of suitable materials keeps the peace with your neighbors and your family by keeping the smelliness away.
Add a balance of brown and green materials to the compost pile. Brown materials include items like wood chips, dry leaves, twigs and newspaper. Green materials include fresh grass clippings and kitchen scraps.
Chop up kitchen scraps into small pieces so they don't clump together into a mushy, smelly pile. Work the kitchen scraps throughout the compost pile.
Throw away kitchen items that contain dairy, fats, meat and bones. These items can cause odor in your compost in addition to drawing pests.
Turn the compost pile with a pitchfork to add oxygen to the materials. The air supports the activity of the bacteria.
Water the compost pile only as needed to keep it moist. Too much water is harmful to the aerobic bacteria necessary to break down the materials.
Add about 2 inches of brown material if you notice an ammonia odor from the pile, indicating that there is too much green material.
Break up large clumps of kitchen scraps if the pile has a rotten smell. Mix the materials into the pile.
All compost bins do give off a little odor. After all, they're full of decomposing kitchen scraps and plant matter! But if your composter is excessively smelly, then there are some things that you can do to get it back under control.
Usually, composting is just as easy as taking out your garbage. You can just walk your kitchen scraps to the composter every day or two, and not worry too much about correctly balancing its contents. Most people mix in yard waste like grass clippings in the summer or dead leaves in the autumn, which helps balance things out.
But sometimes the contents of your composter can build up the wrong proportions of ingredients, which can result in all kinds of unpleasant smells.
As a quick reminder, composting works best when you have the right balance of brown materials and green materials. Brown materials are carbon rich things like dry leaves or small branches. Green materials are nitrogen rich materials such as wet grass clippings, green leaves and food scraps.
By Steffen Latta | Submitted On April 15, 2010
If there is a smelly whiff coming from the direction of your compost heap and you can smell the odor in almost every corner of your garden and property, it is time to apply one of the following tips to get your heap back to a nice "earthy" smelling one.
But before I get there let me explain the reasons behind a bad smelling compost heap.
Truth is compost should not smell bad at all.
Very often a lack of air, i.e. oxygen deficiency is the main problem that leads to anaerobic (without oxygen) conditions within the compost pile.
Having a good aeration throughout the pile is necessary to provide an optimal aerobic (with oxygen) environment for all the active micro organisms (like bacteria) that do the magic and turn all the green waste materials into nice, nutrient rich compost.
If that is not the case and anaerobic conditions are predominantly, fermenting processes will cause the heap to be smelly and wet.
There are three main reasons why this can happen:
1. Overloading the heap with materials so it is too compressed
2. The heap contains too much moisture
3. Sometimes people place layers of soil within the compost
1. Avoid overloading your heap with too many heavy materials.
It is better to add smaller particle sizes of materials and quantities to the compost.
This allows the organisms to break it down much easier and faster as smaller pieces of material have a larger surface area for the organisms to work on compared to bigger pieces that have a smaller surface area.
If you have a lot of green waste it is useful to have more than one compost bin, so you can separate the piles into a new material pile, a turning pile and a matured / finished pile.
2. Avoid too much moisture
Moisture is one of the important factors that aid to a good composting process. Too much moisture however can inhibit or stop the process.
If your compost heap is exposed to heavy rain it is good to cover it or to put a lid on the compost bin.
If you have a lot of moist materials (e.g. fresh green leaves, fresh lawn clippings) within the heap mix some dry materials, such as sawdust, straw or shredded paper into it. The dry materials will absorb the excess moisture and bring the heap back to balance.
3. Avoid adding layers of soil within the compost heap
It is good to mix some soil into a heap to initiate the composting process by adding worms and other active organisms to it.
However, placing too many layers of soil within the heap and on top of each layer of waste material can destroy the compost heap.
The layers of soil cause the heap to compress and it will lead to a smelly and wet mix that takes ages to decompose.
Conclusively, it is important to provide aerobic conditions throughout the compost heap.
To achieve that, you need to turn your heap over regularly.
You can also put plastic pipes with drilled holes along their length vertically into the heap to promote aeration.
At the base of the heap you can place bricks in an open-layered design to provide air channels.
Steffen Latta - Born in Germany, living in New Zealand. Studied horticulture and enjoys working as a gardener and arborist in Auckland's residential gardens.
Virtually all plant material can be composted, ranging from fruit and vegetable peels to coffee grounds and garden clippings. A well-maintained compost will break down smaller pieces of organic matter in weeks, giving you access to fresh soil on a regular basis.
Things You Shouldn’t Compost:
- Inorganic materials, such as: plastic, glass, and metal.
- Fatty and oily foods like grease from a deep fat fryer.
- Meat scraps and bones.
- Dairy products.
- Poop (human or from your pets).
- Large pieces of wood – they’ll take forever to break down.
Along with most plant, vegetable, fruit, garden, and lawn matter, here’s a list of compostables that may surprise you!
Surprising Things You Can Compost:
- Paper products: paper towel, coffee filters, paper bags, news print, cardboard. It’s best to shred paper products if possible to speed breakdown. Even printed papers are safe to compost because most modern inks and dyes are vegetable based.
- Egg shells.
- Egg cartons.
- Tea bags.
Are you dealing with compost odor, or afraid to begin composting because you’re worried about bad smells?
If your compost has a bad odor, then there is something wrong. When the composting process is working correctly, then there are not any bad smells or strong odors.
Compost has a strong ammonia smell
A strong ammonia smell is typically related to too many nitrogen rich materials, and too much moisture.
Add sawdust, shredded leaves, shredded newspaper or shredded cardboard to add more carbon rich materials, dry out the pile, and bring it back into balance. If it’s a bin, leave the lid off in sunny weather so that the moisture can burn off.
Compost smells rotten
A rotten smell is usually related to adding materials to your pile that should not have been composted in the first place. Are you added meat, dairy, grease or bones to your compost pile or bin? If so, stop!
You can try adding more carbon rich materials like leaves and sawdust to bury the smelly materials.
You could dig a hole and bury the entire contents of the bin or pile and start over, avoiding meat, dairy, grease and bones in your next batch. Trench composting takes place underground, but there aren’t any smells because the materials are fully buried.
There are organic products that rapidly end any odors, and they work! I like this BioWish Odor Control product.
Do you have a different kind of stink with your compost?
Leave a comment here and tell us about it, or go to our Composting Questions page for help.
Cheese and other dairy products are among the few organic matters usually compost enthusiasts avoid due to the fact that these materials can make compost to smell and can also attract pests.
However, with proper composting preparation and maintenance, you can add cheese safely to your compost and it will not make your compost smell.
In this article, I looked at these basic composting preparation and maintenance on how to add cheese to the compost. I hope you will find this article helpful. Let me know if you have any questions in the comments section below.